Electronic devices generate heat during operation. Thermal management refers to the ability to keep temperature-sensitive elements in an electronic device within a prescribed operating temperature.
The development of high performance electronic devices now requires more innovative thermal management. Each increase in speed and power generally carries a cost of increased heat generation such that additional innovations must be made to provide proper thermal management.
Several methods have been employed for cooling electronic devices that include high performance integrated circuits. As shown in FIG. 1, one method of cooling these types of integrated circuits is by attaching a heat sink 10 to a heat spreader 12 that is part of an integrated circuit package 14. Integrated circuit package 14 is typically soldered, or plugged into, a motherboard on a computer. The heat sink 10 provides cooling to the integrated circuit package 14 during operation of a computer system that includes integrated circuit package 14.
A thermal interface material 16 is most often used to promote an effective thermal path between integrated heat spreader 12 and heat sink 10. Thermal interface material 16 is typically in the form of a paste or tape.
New thermal interface materials with higher thermal conductivities are continually being developed to meet the requirements for more efficient heat removal. These improvements are necessary to keep the next generation of processors operating at acceptable temperatures. Some of the new thermal interface materials are phase-change materials that provide higher thermal performance. These new materials have been proven to be thermally superior over other types of thermal interface materials.
Some of the new thermal interface materials are inherently sticky and adhere well to a surface on heat sink 10 and/or heat spreader 12 with no special treatment or preparation. Sticky thermal interface materials simplify fabrication of an electronic device that includes integrated circuit package 14 because a sticky thermal interface material 16 is easily attached to heat sink 10. Therefore, heat sink suppliers can easily attach sticky thermal interface materials to heat sinks as one of the last steps in the heat sink fabrication process. Heat sinks with pre-attached thermal interface materials allow heat sink suppliers and electronic device manufacturers to handle the combination as one part.
Many of the highly desirable thermal interface materials do not adhere to a surface. As shown in FIG. 2, suppliers of non-sticky thermal interface materials often spray or overlay an adhesive layer 18 onto an entire surface of thermal interface material 16. Adhesive layer 18 connects one of the entire surfaces of thermal interface material 16 to heat sink 10.
Adhesive layer 18 has a much lower thermal conductivity than thermal interface material 16, so that adhesive layer 18 adversely effects the thermal performance of thermal interface material 16. The poor thermal performance of adhesive layer 18 was acceptable in the past because the magnitude of the thermal penalty introduced by adding adhesive layer 18 was relatively small as compared to the overall thermal resistance of thermal interface material 16. As high performance thermal interface materials have been developed, the additional resistance introduced by applying adhesive layer 18 has become a major portion of the overall thermal resistance between integrated circuit package 14 and heat sink 10.
Therefore, it would be desirable to be able to adhere a non-sticky thermal interface material to a heat sink and/or an integrated circuit package without sacrificing thermal conductivity between the integrated circuit package and the heat sink. Any improvements in assembling non-sticky thermal interface materials to heat sinks and/or integrated circuit packages would also not significantly increase the cost of fabricating electronic devices.